What are some alternatives?
When comparing PDFTK Builder and Birdie PDF Security Remover, you can also consider the following products
PDFsam - PDFsam Basic, a free, open source, multi-platform software designed to split, merge, extract pages, mix and rotate PDF files
SysTools PDF Unlocker - PDF Unlocker software allows users to remove restrictions from PDF documents. Unlock PDF for copy, print, edit, sign, comment, etc., On any Windows & Mac OS. Also, remove known user-level password & owner level password security from PDF files.
Adobe Acrobat DC - Make your job easier with Adobe Acrobat DC, the trusted PDF creator. Use Acrobat to convert, edit and sign PDF files at your desk or on the go.
PDF Password Remover Tool - PDF Password Remover Tool. Free PDF password remover tool by PDF Technologies. Remove passwords from PDF documents.
PDF-Shuffler - PDF-Shuffler is a small python-gtk application, which helps the user to merge or split pdf...
Recover PDF Password - Recover PDF Password for Mac recovers forgotten passwords to PDF and unlocks PDF documents.